1. Nuclear Chemistry
The study of the structure of atomic nuclei and the changes they undergo.

2. Guiding Questions Is radiation dangerous?
Is nuclear power a good choice?
What is nuclear energy?
Are nuclear energy and nuclear bombs both dangerous?
More Specifically...:
Give a brief history of radioactivity
Define nuclear chemistry
State that energy can be converted into matter
List factors that determine stability of a nucleus
Balance nuclear equations
Distinguish between various forms of radiation in terms of penetration depth and energy
Determine the half-life of a radioactive substance.
Define nuclear fusion and fission
Describe a chain reaction
List applications of radioisotopes

3. Radioactive Decay Discovered by Antoine Henri Becquerel in 1896
He saw that photographic plates developed bright spots when exposed to uranium metals

4. © 2003 John Wiley and Sons Publishers
Figure 4.1

5. As you may recall, isotopes are atoms of the same element that have different numbers of neutrons.
Isotopes of atoms with unstable nuclei are called radioisotopes

6. Radioactive Isotopes
Stable Isotopes -Atoms that do not release protons or neutrons from the nucleus and ARE NOT RADIOACTIVE.
Unstable Isotopes - Atoms that spontaneously release protons and neutrons from its nucleus. These isotopes ARE RADIOACTIVE.

7. Band of Stability
The region on a graph which indicates all stable nuclei when the number of neutrons are compared to the number of protons for all stable nuclei

8. Nuclear Reactions
Nuclear reactions are different from chemical reactions
Chemical Reactions
Mass is conserved (doesn’t change)
Small energy changes
No changes in the nuclei; involve ONLY valance electrons
Nuclear Reactions
Small changes in mass
Huge energy changes
protons, neutrons, electrons and gamma rays can be lost or gained

9. Mass Defect Some of the mass can be converted into energy
Shown by a very famous equation!
E=mc2
Energy
Mass
Speed of light

10. Types of Radiation
The effect of an electric field on three types of radiation is shown.
Positively charged alpha particles are deflected toward the negatively charged plate.

11. Figure 4.2: The penetrating power of radiation.
© 2003 John Wiley and Sons Publishers
Figure 4.2: The penetrating power of radiation.

12. Products of Natural Radioactivity
Mass
Particle* Symbol Charge Number Identity
Alpha 4 a Helium nucleus 2
Beta 0 b Electron -1
Gamma 0 g Proton of light
*Sometimes a stream of any of these types of particles is called a ray, as in gamma ray,

13. Figure 4.4: The components of α rays, β rays, and γ rays.
© 2003 John Wiley and Sons Publishers
Figure 4.4: The components of α rays, β rays, and γ rays.

14. Types of radioactive decay
alpha particle emission
loss of a helium nucleus.

16. Types of radioactive decay
Beta decay, Nuclear changes that accompany the emission of a beta particle.

17. b particle emission

18. particle emission
Gamma rays are high-energy (short wavelength) electromagnetic radiation. They are denoted by the symbol.
As you can see from the symbol, both the subscript and superscript are zero.
Thus, the emission of gamma rays does not change the atomic number or mass number of a nucleus.
Gamma rays almost always accompany alpha and beta radiation, as they account for most of the energy loss that occurs as a nucleus decays.

19. Induced Nuclear Reactions
Scientists can also force ( = induce) nuclear reactions by smashing nuclei with alpha, beta and gamma radiation to make the nuclei unstable or

20. BALANCING NUCLEAR EQUATIONS
1. The sums of mass numbers (left superscripts) on each side must be equal.
2. The sums of atomic numbers or nuclear charges (left subscripts) on each side of the equation must be equal.
Examples:
238U 4He Th
214Pb 0 b Bi

21. Balancing Nuclear Equations
Complete the following nuclear equations:
At Bi + ?
Th b + ? -1
Tl b + ?
4He 2 85 83
231Pa 91 90
208Pb 82 81

22. Nuclear Reactions Two types: Fission = the splitting of nuclei
Fusion = the joining of nuclei (they fuse together)
Both reactions involve extremely large amounts of energy
Albert Einstein’s equation E = mc2 illustrates the energy found in even small amounts of matter

23. Nuclear Fission:
Is the splitting of one heavy nucleus into two or more smaller nuclei, as well as some sub-atomic particles and energy.
A heavy nucleus is usually unstable, due to many positive protons pushing apart.
When fission occurs:
Energy is produced.
More neutrons are given off.

24. Nuclear Fission Neutrons are used to make nuclei unstable
It is much easier to crash a neutral neutron than a positive proton into a nucleus to release energy.

25. Nuclear Fission Complete the following nuclear equations:
(a) U + 1n U + ?
(b) 9Be + 1H Li + ?
(c) 9Be + 4He C + ?

26. Fission produces a chain reaction

27. The fusion of hydrogen nuclei
Nuclear Fusion
joining of two light nuclei into one heavier nucleus.
In the core of the Sun, two hydrogen nuclei join under tremendous heat and pressure to form a helium nucleus.
When the helium atom is formed, huge amounts of energy are released.
The fusion of hydrogen nuclei

28. Scientists cannot yet find a safe, and manageable method to harness the energy of nuclear fusion.
“cold fusion” would occur at temperatures and pressures that could be controlled (but we haven’t figured out how to get it to happen)

29. Complete the following nuclear equations, thought to be the source of the energy of some stars.
(a) 1H C ?
(b) 13N 13C + ?
(c) 13C + 1H ?
(d) 1H N ?
(e) 15O 15N + ?
(f) 15N + 1H 12C + ?
Nuclear Fusion

30. Applications Medicine Agriculture Energy Chemotherapy Power pacemakers
Diagnostic tracers
Agriculture
Irradiate food
Pesticide
Energy
Fission
Fusion

31. X-ray examination of luggage at a security station.
© 2003 John Wiley and Sons Publishers
Courtesy Robert Maass/Corbis Images
X-ray examination of luggage at a security station.

32. Food Irradiation
Food can be irradiated with g rays from 60Co or 137Cs.
Irradiated milk has a shelf life of 3 mo. without refrigeration.
USDA has approved irradiation of meats and eggs.

33. © 2003 John Wiley and Sons Publishers
Courtesy Custom Medical Stock Photo
An image of a thyroid gland obtained through the use of radioactive iodine.

34. Images of human lungs obtained from a γ-ray scan.
© 2003 John Wiley and Sons Publishers
Images of human lungs obtained from a γ-ray scan. A compound containing radioactive technetium-99m was the source of the radiation.
Courtesy CNRI/Phototake
Images of human lungs obtained from a γ-ray scan.

35. A cancer patient receiving radiation therapy.
© 2003 John Wiley and Sons Publishers
Courtesy Kelley Culpepper/Transparencies, Inc.
A cancer patient receiving radiation therapy.

36. © 2003 John Wiley and Sons Publishers
Courtesy Scott Camazine/Photo Researchers
The world’s first atomic explosion, July 16, 1945 at Alamogordo, New Mexico.

37. © 2003 John Wiley and Sons Publishers
Courtesy Shigeo Hayashi
Remains of a building after the explosion of the uranium bomb at Hiroshima, August 6, 1945.

38. Cooling towers of a nuclear power plant.
© 2003 John Wiley and Sons Publishers
Courtesy David Bartruff/Corbis Images
Cooling towers of a nuclear power plant.

39. © 2003 John Wiley and Sons Publishers
Courtesy Sipa Press
The nuclear power plant at Chernobyl, after the accident of April 16, 1986.

40. Challenges of Nuclear Power
Disposal of waste products

41. Challenges of Nuclear Power
Disposal of waste products
Hazardous wastes produced by nuclear reactions are problematic.
Some waste products, like fuel rods, can be re-used
Some products are very radioactive, and must be stored away from living things.
Most of this waste is buried underground, or stored in concrete
It takes 20 half-lives (thousands of years) before the material is safe.

42. © 2003 John Wiley and Sons Publishers
Courtesy Yucca Mountain Project
Construction of a tunnel that will be used for burial of radioactive wastes deep within Yucca Mountain, Nevada.

43. Disposal of radioactive wastes by burial in a shallow pit.
© 2003 John Wiley and Sons Publishers
Courtesy Matthew Neal McVay/Stone/Getty Images
Disposal of radioactive wastes by burial in a shallow pit.

44. © 2003 John Wiley and Sons Publishers
Courtesy AP/Wide World Photos
Albert Einstein, he discovered the equation that relates mass and energy.